pub struct Canonical<'tcx, V> {
    pub max_universe: UniverseIndex,
    pub variables: CanonicalVarInfos<'tcx>,
    pub value: V,
}
Expand description

A “canonicalized” type V is one where all free inference variables have been rewritten to “canonical vars”. These are numbered starting from 0 in order of first appearance.

Fields

max_universe: UniverseIndexvariables: CanonicalVarInfos<'tcx>value: V

Implementations

Allows you to map the value of a canonical while keeping the same set of bound variables.

WARNING: This function is very easy to mis-use, hence the name! In particular, the new value W must use all the same type/region variables in precisely the same order as the original! (The ordering is defined by the TypeFoldable implementation of the type in question.)

An example of a correct use of this:

let a: Canonical<'_, T> = ...;
let b: Canonical<'_, (T,)> = a.unchecked_map(|v| (v, ));

An example of an incorrect use of this:

let a: Canonical<'tcx, T> = ...;
let ty: Ty<'tcx> = ...;
let b: Canonical<'tcx, (T, Ty<'tcx>)> = a.unchecked_map(|v| (v, ty));

Returns true if this represents a substitution of the form [?0, ?1, ?2], i.e., each thing is mapped to a canonical variable with the same index.

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

Traverses the type in question, typically by calling try_fold_with on each field/element. This is true even for types of interest such as Ty. This should only be called within TypeFolder methods, when non-custom traversals are desired for types of interest. Read more

Traverses the type in question, typically by calling visit_with on each field/element. This is true even for types of interest such as Ty. This should only be called within TypeVisitor methods, when non-custom traversals are desired for types of interest. Read more

The main entry point for folding. To fold a value t with a folder f call: t.try_fold_with(f). Read more

A convenient alternative to try_fold_with for use with infallible folders. Do not override this method, to ensure coherence with try_fold_with. Read more

A convenient alternative to try_super_fold_with for use with infallible folders. Do not override this method, to ensure coherence with try_super_fold_with. Read more

The entry point for visiting. To visit a value t with a visitor v call: t.visit_with(v). Read more

Returns true if self has any late-bound regions that are either bound by binder or bound by some binder outside of binder. If binder is ty::INNERMOST, this indicates whether there are any late-bound regions that appear free. Read more

Returns true if this self has any regions that escape binder (and hence are not bound by it). Read more

“Free” regions in this context means that it has any region that is not (a) erased or (b) late-bound. Read more

True if there are any un-erased free regions.

Indicates whether this value references only ‘global’ generic parameters that are the same regardless of what fn we are in. This is used for caching. Read more

True if there are any late-bound regions

Indicates whether this value still has parameters/placeholders/inference variables which could be replaced later, in a way that would change the results of impl specialization. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

This method turns the parameters of a DepNodeConstructor into an opaque Fingerprint to be used in DepNode. Not all DepNodeParams support being turned into a Fingerprint (they don’t need to if the corresponding DepNode is anonymous). Read more

This method tries to recover the query key from the given DepNode, something which is needed when forcing DepNodes during red-green evaluation. The query system will only call this method if fingerprint_style() is not FingerprintStyle::Opaque. It is always valid to return None here, in which case incremental compilation will treat the query as having changed instead of forcing it. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.